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Aoun M, Siegel C, Windham G, Williams W, Nelson R. Application of reflectance spectroscopy to identify maize genotypes and aflatoxin levels in single kernels. WORLD MYCOTOXIN J 2022. [DOI: 10.3920/wmj2021.2750] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Spectroscopy is a rapid, non-destructive, and low-cost analytical technique that has the potential to complement more resource-intensive analytical methods. We explored the use of spectral methods to differentiate maize genotypes and assess aflatoxin (AF) contamination in maize kernels. We compared the performance of two instruments: a research-grade ultraviolet-visible-near infrared (UV-Vis-NIR) spectrometer that measures reflectance from 304 -1,085 nm, and a miniaturised NIR spectrometer that measures reflectance from 740-1,070 nm. Both systems were used to predict AF levels in maize kernels from a single genotype and across 10 genotypes, and to predict genotype for the latter. A partial least square discriminant analysis model was trained on 70% of the kernels and tested on the remaining 30%. The classification accuracy for 10 maize genotypes was 71-72% using the UV-Vis-NIR instrument on 1,170 kernels, and 65-66% using the NIR device on 740 kernels. The classification accuracy for 247 AF-contaminated kernels of a single genotype using the UV-Vis-NIR instrument was 71, 82, and 92% for AF thresholds of 20, 100, and 1000 μg/kg, respectively. Using the same spectrometer on 872 kernels from 10 genotypes, AF classification accuracy was 67, 90, and 95% in validation sets for AF thresholds of 20, 100, and 1000 μg/kg, respectively. The UV-Vis-NIR instrument and the NIR device had similar classification accuracies for AF thresholds of 100 and 1000 μg/kg, whereas the NIR device had higher accuracy for the AF threshold of 20 μg/kg. Reflectance spectroscopy outperformed visual sorting and the bright greenish yellow fluorescence test in identifying AF levels. Applying spectral analysis to estimate mycotoxin levels and to identify maize genotypes could contribute to regional toxin surveillance and action efforts. Further, using AF-associated spectral features for grain sorting can reduce AF exposure.
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Affiliation(s)
- M. Aoun
- School of Integrative Plant Science, Cornell University, Ithaca, NY 14853, USA
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, OK 74078, USA
| | - C. Siegel
- School of Integrative Plant Science, Cornell University, Ithaca, NY 14853, USA
| | - G.L. Windham
- USDA, Agricultural Research Service, Corn Host Plant Resistance Research Unit, Mississippi State, MS 39762, USA
| | - W.P. Williams
- USDA, Agricultural Research Service, Corn Host Plant Resistance Research Unit, Mississippi State, MS 39762, USA
| | - R.J. Nelson
- School of Integrative Plant Science, Cornell University, Ithaca, NY 14853, USA
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Liu S, Wang J, Guo N, Sun H, Ma H, Zhang H, Shi J. Talaromyces funiculosus, a Novel Causal Agent of Maize Ear Rot and Its Sensitivity to Fungicides. PLANT DISEASE 2021; 105:3978-3984. [PMID: 34156277 DOI: 10.1094/pdis-04-21-0686-re] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Ear rot is one of the most prevalent and destructive diseases of maize. During field surveys, it was found that a Penicillium ear rot broke out in some areas of Shanxi, Shaanxi, Hebei, and Tianjin in China, with an incidence of 3 to 90%. A Penicillium sp. was isolated from diseased kernels covered with greyish green mold, and three isolates were identified by morphologic and molecular characteristics. The pathogenicity of isolate ZBS205 to maize ears was further determined by artificial inoculation in a field. Furthermore, the sensitivity of isolate ZBS205 against six commonly used fungicides was also evaluated. According to macro- and micromorphologic characteristics, isolate ZBS205 was generally identical to Talaromyces funiculosus (teleomorph of Penicillium funiculosum). The partial gene sequences of the nuclear ribosomal ITS1-5.8S-ITS2 (ITS) region, β-tubulin, putative ribosome biogenesis protein (Tsr1), and the second largest subunit of the RNA polymerase II (RPB2) from isolates ZBS205, D49-1, and S73-1 showed the highest nucleotide identity to T. funiculosus strain X33, and the phylogenetic analysis conducted by the neighbor-joining method with the combined data of the four genes demonstrated that these three isolates clustered with T. funiculosus strain X33. These results suggested that the fungus isolated from diseased maize kernels was T. funiculosus. Pathogenicity testing showed that the T. funiculosus isolate ZBS205 was pathogenic to maize ears, which showed symptoms of rotted cob and deteriorated kernels. This is the first report of T. funiculosus as the definitive pathogen causing maize ear rot. The result of fungal sensitivity against fungicides showed that pyraclostrobin exhibited the highest toxicity to mycelial growth and could be used as a candidate agent for the prevention and control of T. funiculosus ear rot. The results of the present study provide a basis for understanding ear rot caused by T. funiculosus, and they should play an important role in disease management.
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Affiliation(s)
- Shusen Liu
- Plant Protection Institute, Hebei Academy of Agricultural and Forestry Sciences, IPM (Integrated Pest Management) Centre of Hebei Province; Key Laboratory of IPM on Crops in Northern Region of North China, Ministry of Agriculture and Rural Affairs, Baoding 071000, China
| | - Jinhui Wang
- College of Plant Protection, Hebei Agricultural University, Baoding 071001, China
| | - Ning Guo
- Plant Protection Institute, Hebei Academy of Agricultural and Forestry Sciences, IPM (Integrated Pest Management) Centre of Hebei Province; Key Laboratory of IPM on Crops in Northern Region of North China, Ministry of Agriculture and Rural Affairs, Baoding 071000, China
| | - Hua Sun
- Plant Protection Institute, Hebei Academy of Agricultural and Forestry Sciences, IPM (Integrated Pest Management) Centre of Hebei Province; Key Laboratory of IPM on Crops in Northern Region of North China, Ministry of Agriculture and Rural Affairs, Baoding 071000, China
| | - Hongxia Ma
- Plant Protection Institute, Hebei Academy of Agricultural and Forestry Sciences, IPM (Integrated Pest Management) Centre of Hebei Province; Key Laboratory of IPM on Crops in Northern Region of North China, Ministry of Agriculture and Rural Affairs, Baoding 071000, China
| | - Haijian Zhang
- Plant Protection Institute, Hebei Academy of Agricultural and Forestry Sciences, IPM (Integrated Pest Management) Centre of Hebei Province; Key Laboratory of IPM on Crops in Northern Region of North China, Ministry of Agriculture and Rural Affairs, Baoding 071000, China
| | - Jie Shi
- Plant Protection Institute, Hebei Academy of Agricultural and Forestry Sciences, IPM (Integrated Pest Management) Centre of Hebei Province; Key Laboratory of IPM on Crops in Northern Region of North China, Ministry of Agriculture and Rural Affairs, Baoding 071000, China
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Chalivendra S, Huang F, Busman M, Williams WP, Ham JH. Low Aflatoxin Levels in Aspergillus flavus-Resistant Maize Are Correlated With Increased Corn Earworm Damage and Enhanced Seed Fumonisin. FRONTIERS IN PLANT SCIENCE 2020; 11:565323. [PMID: 33101334 PMCID: PMC7546873 DOI: 10.3389/fpls.2020.565323] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/24/2020] [Accepted: 08/19/2020] [Indexed: 06/11/2023]
Abstract
Preharvest mycotoxin contamination of field-grown crops is influenced not only by the host genotype, but also by inoculum load, insect pressure and their confounding interactions with seasonal weather. In two different field trials, we observed a preference in the natural infestation of corn earworm (CEW; Helicoverpa zea Boddie) to specific maize (Zea mays L.) genotypes and investigated this observation. The field trials involved four maize lines with contrasting levels of resistance to Aspergillus flavus. The resistant lines had 7 to 14-fold greater infested ears than the susceptible lines. Seed aflatoxin B1 (AF) levels, in mock- and A. flavus-inoculated ears were consistent with genotype resistance to A. flavus, in that the resistant lines showed low levels of AF (<30 ppb), whereas the susceptible lines had up to 500 ppb. On the other hand, CEW infestation showed a positive correlation with seed fumonisins (FUM) contamination by native Fusarium verticillioides strains. We inferred that the inverse trend in the correlation of AF and FUM with H. zea infestation may be due to a differential sensitivity of CEW to the two mycotoxins. This hypothesis was tested by toxin-feeding studies. H. zea larvae showed decreasing mass with increasing AF in the diet and incurred >30% lethality at 250 ppb. In contrast, CEW was tolerant to fumonisin with no significant loss in larval mass even at 100 ppm, implicating the low seed aflatoxin content as a predominant factor for the prevalence of CEW infestation and the associated fumonisin contamination in A. flavus resistant maize lines. Further, delayed flowering of the two resistant maize lines might have contributed to the pervasive H. zea damage of these lines by providing young silk for egg-laying. These results highlight the need for integrated strategies targeting mycotoxigenic fungi as well as their insect vectors for enhanced food safety.
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Affiliation(s)
- Subbaiah Chalivendra
- Department of Plant Pathology and Crop Physiology, Louisiana State University AgCenter, Baton Rouge, LA, United States
| | - Fangneng Huang
- Department of Entomology, Louisiana State University AgCenter, Baton Rouge, LA, United States
| | - Mark Busman
- Bacterial Foodborne Pathogens and Mycology Research Unit, USDA-ARS-NCAUR, Peoria, IL, United States
| | - W. Paul Williams
- Corn Host Plant Resistance Research Unit, USDA-ARS, Mississippi State, MS, United States
| | - Jong Hyun Ham
- Department of Plant Pathology and Crop Physiology, Louisiana State University AgCenter, Baton Rouge, LA, United States
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Pfliegler WP, Pócsi I, Győri Z, Pusztahelyi T. The Aspergilli and Their Mycotoxins: Metabolic Interactions With Plants and the Soil Biota. Front Microbiol 2020; 10:2921. [PMID: 32117074 PMCID: PMC7029702 DOI: 10.3389/fmicb.2019.02921] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 12/04/2019] [Indexed: 01/06/2023] Open
Abstract
Species of the highly diverse fungal genus Aspergillus are well-known agricultural pests, and, most importantly, producers of various mycotoxins threatening food safety worldwide. Mycotoxins are studied predominantly from the perspectives of human and livestock health. Meanwhile, their roles are far less known in nature. However, to understand the factors behind mycotoxin production, the roles of the toxins of Aspergilli must be understood from a complex ecological perspective, taking mold-plant, mold-microbe, and mold-animal interactions into account. The Aspergilli may switch between saprophytic and pathogenic lifestyles, and the production of secondary metabolites, such as mycotoxins, may vary according to these fungal ways of life. Recent studies highlighted the complex ecological network of soil microbiotas determining the niches that Aspergilli can fill in. Interactions with the soil microbiota and soil macro-organisms determine the role of secondary metabolite production to a great extent. While, upon infection of plants, metabolic communication including fungal secondary metabolites like aflatoxins, gliotoxin, patulin, cyclopiazonic acid, and ochratoxin, influences the fate of both the invader and the host. In this review, the role of mycotoxin producing Aspergillus species and their interactions in the ecosystem are discussed. We intend to highlight the complexity of the roles of the main toxic secondary metabolites as well as their fate in natural environments and agriculture, a field that still has important knowledge gaps.
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Affiliation(s)
- Walter P. Pfliegler
- Department of Molecular Biotechnology and Microbiology, Institute of Biotechnology, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary
| | - István Pócsi
- Department of Molecular Biotechnology and Microbiology, Institute of Biotechnology, Faculty of Science and Technology, University of Debrecen, Debrecen, Hungary
| | - Zoltán Győri
- Institute of Nutrition, Faculty of Agricultural and Food Sciences and Environmental Management, University of Debrecen, Debrecen, Hungary
| | - Tünde Pusztahelyi
- Central Laboratory of Agricultural and Food Products, Faculty of Agricultural and Food Sciences and Environmental Management, University of Debrecen, Debrecen, Hungary
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Zhou S, Zhang YK, Kremling KA, Ding Y, Bennett JS, Bae JS, Kim DK, Ackerman HH, Kolomiets MV, Schmelz EA, Schroeder FC, Buckler ES, Jander G. Ethylene signaling regulates natural variation in the abundance of antifungal acetylated diferuloylsucroses and Fusarium graminearum resistance in maize seedling roots. THE NEW PHYTOLOGIST 2019; 221:2096-2111. [PMID: 30289553 DOI: 10.1111/nph.15520] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2018] [Accepted: 09/26/2018] [Indexed: 05/20/2023]
Abstract
The production and regulation of defensive specialized metabolites play a central role in pathogen resistance in maize (Zea mays) and other plants. Therefore, identification of genes involved in plant specialized metabolism can contribute to improved disease resistance. We used comparative metabolomics to identify previously unknown antifungal metabolites in maize seedling roots, and investigated the genetic and physiological mechanisms underlying their natural variation using quantitative trait locus mapping and comparative transcriptomics approaches. Two maize metabolites, smilaside A (3,6-diferuloyl-3',6'-diacetylsucrose) and smiglaside C (3,6-diferuloyl-2',3',6'-triacetylsucrose), were identified that could contribute to maize resistance against Fusarium graminearum and other fungal pathogens. Elevated expression of an ethylene signaling gene, ETHYLENE INSENSITIVE 2 (ZmEIN2), co-segregated with a decreased smilaside A : smiglaside C ratio. Pharmacological and genetic manipulation of ethylene availability and sensitivity in vivo indicated that, whereas ethylene was required for the production of both metabolites, the smilaside A : smiglaside C ratio was negatively regulated by ethylene sensitivity. This ratio, rather than the absolute abundance of these two metabolites, was important for maize seedling root defense against F. graminearum. Ethylene signaling regulates the relative abundance of the two F. graminearum-resistance-related metabolites and affects resistance against F. graminearum in maize seedling roots.
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Affiliation(s)
- Shaoqun Zhou
- Boyce Thompson Institute, 533 Tower Road, Ithaca, NY, 14853, USA
- Plant Biology Section, School of Integrated Plant Science, Cornell University, Ithaca, NY, 14853, USA
| | - Ying K Zhang
- Boyce Thompson Institute, 533 Tower Road, Ithaca, NY, 14853, USA
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Karl A Kremling
- Plant Breeding and Genetics Section, Cornell University, Ithaca, NY, 14853, USA
| | - Yezhang Ding
- Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA, 92093, USA
| | - John S Bennett
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX, 77840, USA
| | - Justin S Bae
- Boyce Thompson Institute, 533 Tower Road, Ithaca, NY, 14853, USA
| | - Dean K Kim
- Boyce Thompson Institute, 533 Tower Road, Ithaca, NY, 14853, USA
| | | | - Michael V Kolomiets
- Department of Plant Pathology and Microbiology, Texas A&M University, College Station, TX, 77840, USA
| | - Eric A Schmelz
- Section of Cell and Developmental Biology, University of California at San Diego, La Jolla, CA, 92093, USA
| | | | - Edward S Buckler
- Plant Breeding and Genetics Section, Cornell University, Ithaca, NY, 14853, USA
- United States Department of Agriculture-Agricultural Research Service, Robert W. Holley Center for Agriculture and Health, Ithaca, NY, 14853, USA
| | - Georg Jander
- Boyce Thompson Institute, 533 Tower Road, Ithaca, NY, 14853, USA
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Chalivendra SC, DeRobertis C, Chang PK, Damann KE. Cyclopiazonic Acid Is a Pathogenicity Factor for Aspergillus flavus and a Promising Target for Screening Germplasm for Ear Rot Resistance. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2017; 30:361-373. [PMID: 28447887 DOI: 10.1094/mpmi-02-17-0026-r] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Aspergillus flavus, an opportunistic pathogen, contaminates maize and other key crops with carcinogenic aflatoxins (AFs). Besides AFs, A. flavus makes many more secondary metabolites (SMs) whose toxicity in insects or vertebrates has been studied. However, the role of SMs in the invasion of plant hosts by A. flavus remains to be investigated. Cyclopiazonic acid (CPA), a neurotoxic SM made by A. flavus, is a nanomolar inhibitor of endoplasmic reticulum calcium ATPases (ECAs) and a potent inducer of cell death in plants. We hypothesized that CPA, by virtue of its cytotoxicity, may serve as a key pathogenicity factor that kills plant cells and supports the saprophytic life style of the fungus while compromising the host defense response. This proposal was tested by two complementary approaches. A comparison of CPA levels among A. flavus isolates indicated that CPA may be a determinant of niche adaptation, i.e., isolates that colonize maize make more CPA than those restricted only to the soil. Further, mutants in the CPA biosynthetic pathway are less virulent in causing ear rot than their wild-type parent in field inoculation assays. Additionally, genes encoding ECAs are expressed in developing maize seeds and are induced by A. flavus infection. Building on these results, we developed a seedling assay in which maize roots were exposed to CPA, and cell death was measured as Evans Blue uptake. Among >40 maize inbreds screened for CPA tolerance, inbreds with proven susceptibility to ear rot were also highly CPA sensitive. The publicly available data on resistance to silk colonization or AF contamination for many of the lines was also broadly correlated with their CPA sensitivity. In summary, our studies show that i) CPA serves as a key pathogenicity factor that enables the saprophytic life style of A. flavus and ii) maize inbreds are diverse in their tolerance to CPA. Taking advantage of this natural variation, we are currently pursuing both genome-wide and candidate gene approaches to identify novel components of maize resistance to Aspergillus ear rot.
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Affiliation(s)
| | | | - Perng-Kuang Chang
- 2 USDA-Southern Region Research Center, New Orleans, LA 70124, U.S.A
| | - Kenneth E Damann
- 1 Louisiana State University Ag Center, Baton Rouge, LA 70803, U.S.A.; and
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Abstract
Aflatoxin contamination of maize grain is a huge economic and health problem, causing death and increased disease burden in much of the developing world and income loss in the developed world. Despite the gravity of the problem, deployable solutions are still being sought. In the past 15 years, much progress has been made in creating resistant maize inbred lines; mapping of genetic factors associated with resistance; and identifying possible resistance mechanisms. This review highlights this progress, most of which has occurred since the last time a review was published on this topic. Many of the needs highlighted in the last reviews have been addressed, and several solutions, taken together, can now greatly reduce the aflatoxin problem in maize grain. Continued research will soon lead to further solutions, which promise to further reduce and even eliminate the problem completely.
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Santiago R, Barros-Rios J, Malvar RA. Impact of cell wall composition on maize resistance to pests and diseases. Int J Mol Sci 2013; 14:6960-80. [PMID: 23535334 PMCID: PMC3645672 DOI: 10.3390/ijms14046960] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 03/19/2013] [Accepted: 03/20/2013] [Indexed: 11/16/2022] Open
Abstract
In cereals, the primary cell wall is built of a skeleton of cellulosic microfibrils embedded in a matrix of hemicelluloses and smaller amounts of pectins, glycoproteins and hydroxycinnamates. Later, during secondary wall development, p-coumaryl, coniferyl and sinapyl alcohols are copolymerized to form mixed lignins. Several of these cell wall components show a determinative role in maize resistance to pest and diseases. However, defense mechanisms are very complex and vary among the same plant species, different tissues or even the same tissue at different developmental stages. Thus, it is important to highlight that the role of the cell wall components needs to be tested in diverse genotypes and specific tissues where the feeding or attacking by the pathogen takes place. Understanding the role of cell wall constituents as defense mechanisms may allow modifications of crops to withstand pests and diseases.
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